The basic concept of the project is the development of oral synthetic fibrinolytic agents, in other words, thrombus-dissolving pill. Previous investigations carried out by this investigator have indicated that such an approach is feasible. A correlation between the chemical structure and the fibrinolytic potency of the discovered thrombus-dissolving agents was established and will be further investigated. The only partially known mechanism of action of the synthetic fibrinolytic agents will be extensively explored. Potential platelet aggregation-preventing properties of the synthetic fibrinolytic agents is another aspect of the current research on the subject that is planned. Particular attention will be paid to the enhancing effects of the synthetic fibrinolytic agents on the fibrinolytic action of streptokinase and urokinase. This would permit a considerable reduction in the amount of these expensive activators that it would be necessary to use. Some synthetic fibrinolytic agents will be tested in animals thus extending a line of research which is already in progress.